Many man-made dwellings and other structures have an attic space which is separated from the living, working, or storage space by a ceiling. The roofs of these structures often become quite hot because of direct exposure to the electromagnetic rays from the sun. One purpose of the attic space is to provide an air space to insulate the living, working, or storage space below the ceiling from the great amount of energy which is radiated, conducted, and convected into the attic space from the roofing materials. The insulation effectiveness of the attic space varies substantially depending upon the provisions for natural circulation of outside air, provision of power ventilators to induce outside air circulation, and the thermal conductivity of the construction materials utilized for the ceiling and insulating substances.
The amount of energy conducted from the attic space through the ceiling may be diminished by cooling the air within the attic space. Evaporative cooling is especially suitable because of lower construction cost, lower installation cost, and lower operating cost as compared with alternatives such as compressor dependent refrigeration cycles. Since most attic spaces are not inhabited, the greatest human comfort objections to evaporative coolers such as high relative humidity and odor emission are not applicable.
The inventions described in the prior art of the invention are not well suited to cooling the air in attics. The prior art coolers are designed to humidify and cool very dry air for direct injection into living and working spaces for people. The coolers utilize relatively large amounts of energy for circulating water and forcing air through evaporation pads. The water must to treated, filtered, and otherwise purified to prevent growth of algae and other biological species which thrive in the operating conditions of evaporative coolers. The evaporative coolers require maintenance for cleaning and replacing evaporation pads. The motors, blowers, and pumps require periodic service and/or replacement.